The present invention relates to rotary cutting tools for use chiefly in surface cutting such as, for example, a face milling cutter or the like and, more particularly, to a rotary cutting tool capable of successively processing chips generated during cutting.
Referring to FIGS. 40 through 42 of the attached drawings, there is shown a face milling cutter which is an example of the conventional rotary cutting tools for use in surface cutting of a workpiece.
The face milling cutter has a cutter body 1 substantially in the form of a cylinder. A plurality of insert mounting seats 2 are formed at an outer periphery of a forward end of the cutter body 1 in circumferentially equidistantly spaced relation to each other, and open toward the forward-end face and an outer peripheral surface of the cutter body 1. One or a plurality of cutting insert 3 are detachably mounted respectively to the insert mounting seats 2 by respective wedge elements 5 which are tightened respectively by clamp screws 4.
On the other hand, chip pockets 6 having their respective arcuate wall surfaces are formed on the outer peripheral surface of the cutter body 1 at respective locations which face toward cutting face of the respective insert 3. A central bore 7 is formed at a center of the cutter body 1 and extends axially therethrough.
In the face milling cutter constructed as above, an arbor 10 is mounted to a main spindle 8 of a machine body through a plurality of keys 9. The arbor 10 has a fitting shaft 10a which is fitted in the central bore 7 in the cutter body 1. A tightening bolt 12 is screwed into the fitting shaft 10a. Thus, the cutter body 1 is fixedly mounted together to the main spindle 8. Under this condition, the cutter body 1 is rotated about the axis of the main spindle 8 by the same, and is fed in a direction perpendicular to the axis of the spindle 8. In this manner, a surface of the workpiece is processed by the insert 3. Chips generated at this time are guided by the wall surfaces of the respective chip pockets 6 from faces 3b of the respective insert 3, and are rounded off. The rounded-off chips are discharged peripherally outwardly of the cutter body 1.
The face milling cutter described above has the following drawback or disadvantage. That is, since the face milling cutter merely guides and discharges the generated chips peripherally outwardly of the face milling cutter, the chips are accumulated adjacent the insert 3. As a result, not only is the operational environment deteriorated, but also a danger sometimes occurs during operation. Further, a considerable time is taken to process the chips after completion of the cutting.
Moreover, the conventional face milling cutter has also the following disadvantage. That is, since the chips are gradually accumulated on the workpiece, a table of the machine tool and the like, as the cutting continues, thermal deformation occurs in the workpiece or the machine tool due to heat of the chips. Thus, working or processing accuracy is deteriorated, and the chips will bite into the insert 3 so that the quality of the cut surface is damaged.
Furthermore, the chips adjacent the insert will enter between sliding surfaces or the like of the machine tool. Thus, it is apprehended that the machine tool per se is deteriorated in accuracy or is reduced in service life.
The above-discussed problems are particularly important in a machining center which requires unmanned operation for a long period of time.